Features/VirtStorageManagement

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(Background)
Line 25: Line 25:
 
for each OS.
 
for each OS.
  
When a new application is deployed, whoever is driving the deployment
+
When a new application is deployed the SAN
typically makes three parallel requests, one to the facilities team to
+
admins provision the storage and notify whichever OS team is responsible for the server to
get the hardware racked and wired, one to the server admins for the OS
+
installation, and one to the SAN admins for storage provisioning.  The
+
server request blocks until the hardware is available and the storage
+
allocation request completes.  When the storage is available, the SAN
+
admins notify whichever OS team is responsible for the server to
+
 
proceed with the OS install.
 
proceed with the OS install.
  
Line 50: Line 45:
 
libvirt's APIs, to identify storage precisely and validate that the
 
libvirt's APIs, to identify storage precisely and validate that the
 
storage intended is actually used.
 
storage intended is actually used.
 
When the new server is virtual, the entire process becomes an exercise
 
in software configuration.  Instead of making a request of the
 
facilities team to buy, rack and wire a new box, whoever is driving
 
the process requests creation of a new VM.  With the right management
 
tools, the OS team who will be installing the server can be given
 
rights to create VMs and the number of teams involved can be reduced
 
to two: the OS admins and the SAN admins.  That level of organization
 
requires that the tool used to manage the VMs be capable of
 
discovering and presenting SAN storage to VMs.
 
  
 
While libvirt is currently capable of using SAN storage, it lacks the
 
While libvirt is currently capable of using SAN storage, it lacks the

Revision as of 21:15, 26 February 2009

Contents

Summary

Enable VM hosts to discover new SAN storage, issue NPIV operations and do basic configuration of multipath devices.

Owner

Current status

  • Targeted release: Fedora 11
  • Last updated: 2009-02-25
  • Percentage of completion: 5%

Detailed Description

Background

Guest virtual machines can currently use SAN storage and multipath devices, but administrators must do the storage configuration manually using separate tools from libvirt. This feature will permit administrators to discover storage and present it to virtual machines using libvirt.

Datacenter operations are usually split along functional lines: the facilities management team, the server administration team, the SAN administration team, and others (network, etc.) not relevant to this discussion. Within the server admin group, there are often sub-groups for each OS.

When a new application is deployed the SAN admins provision the storage and notify whichever OS team is responsible for the server to proceed with the OS install.

There may be more or less information transmitted from the SAN admins to the server admins when the storage becomes available. The minimal message is something along the lines of, "I've provisioned the LUNs, and you should be able to see them now. I gave you LUNs 27, 28, 29 and 53." The server admin may not know what targets or hosts the new storage is accessible through, but a rescan of all host adapters will show up new logical units with numbers 27, 28, 29 and 53 on some target on some host, and the server admin assumes that's the new storage.

The functionality described here does not attempt to address the many possible failures that can result from the communication between the storage admins and the server admins described above. What we are doing is providing a framework to make the described process work within its limitations. Perhaps more importantly, we create a foundation for work that will make it possible for admins, using only libvirt's APIs, to identify storage precisely and validate that the storage intended is actually used.

While libvirt is currently capable of using SAN storage, it lacks the ability to trigger scans for new storage, create virtual host adapters using NPIV and manage multipath devices. The OS admin team that manages the VM host must get involved to get the VM host to recognize the new storage. Giving libvirt the ability to manage storage allows the OS admin team responsible for the guest OS to complete the VM build out itself.

Implementation

The libvirt APIs already permit storage discovery and pool creation. These functions will be extended to discover storage on a per-SCSI-host basis and multipath devices. The pool create and destroy functions will be extended to understand multipath and NPIV.

Benefit to Fedora

Administrators will be able to provision storage for VMs from the single set of tools that they are already using to manage the VMs.

Scope

As described above, changes are required in libvirt. Eventually the tools using libvirt will need to be updated to take advantage of the new features, but that is not within the scope of this work.

TODO

  • Implement storage discovery
  • Implement NPIV operations
  • Implement multipath configuration

Completed

  • none

How To Test

  1. Use virsh to discover and configure SAN storage.
  2. Use virsh to issue NPIV operations.
  3. Use virsh to configure multipath devices.
  4. Assign SAN and multipath storage to VMs.

User Experience

See the previous section.

Dependencies

None, outside of the implementation efforts detailed above.

Contingency Plan

This functionality is independent of all other features. If it is not ready, administrators can continue to configure storage manually.

Documentation

Release Notes

Fedora 11 adds the ability in libvirt to discover storage on a per-SCSI-host basis, issue NPIV operations and configure multipath devices. This enables administrators to discover, configure and provision storage for virtual machines without having to use multiple tools.

Comments and Discussion